Wildly diverse and far more often helpful than harmful, microbes live in complex societies, ables to communicate with each other and live symbiotically with their host organisms. From antibiotic-resistant strains to the squid's luminescent bacteria, the eradication of malarial mosquitos to "terrorist" bacteria and the mysteries of gut flora, here is a comprehensive overview of microbiology. Permanent Secretary of the Academy of Sciences, Professor Pascale Cossart of the Pasteur Institute has won many international prizes.